It is common to dye yarns that are used in various goods, such as carpeting. In some instances, yarns having intermittent colored segments are desired in the production of such goods.
A known method for intermittently coloring yarn comprises knitting non-dyed yarn into tubing, applying multiple dyes (e.g., using a printing process) on the tubing, steaming to cure the dyes, washing to remove excess dyes, and de-knitting the tubing to form the final intermittently colored yarn. This process is very tedious and expensive, so much so that it severely restricts penetration of intermittently colored yarn into the market.
Another somewhat lower cost process of making intermittently colored yarn comprises a continuous dyeing process in which 36-48 ends of non-dyed yarn are processed together as warp. Multiple dyes are sprayed on the warp followed by subsequent steaming, washing, and drying, with subsequent winding to form 36-48 individual yarn packages. This process primarily works with high interlace, low crimp bulked continuous filament (BCF) yarns. It does not work well with most of the regular BCF yarns with normal crimp and interlace levels due to frequent entanglement which tends to occur with such yarns during the winding process as neighboring ends tend to stick together due to the presence of crimp. Carpets made from yarns with such high interlace and low crimp as required for the known spray dyeing processes are perceived to be of lower quality, and do not participate in premium offerings.
Even earlier examples of the background art include a variety of devices where yarn is compressed or tightly crimped and dye is applied via jets or tapes in tightly confined spaces. These processes, as disclosed in U.S. Pat. Nos. 3,135,039, 3,644,969, 3,751,778, 4,068,502, 4,177,037, and 4,742,699, share two common shortcomings. They provide poor productivity due to slow operating speeds, and they are not able to accurately reproduce an intermittent color appearance owing to excessive, unintended dye transfer to the yarn by the surfaces of the confining spaces into which dye is applied.